Originally Posted by
makeinu
Many of us around the folding bike forum are engineers and, as engineers, we cringe at the seemingly endless supply of fallacies perpetuated about small wheels (by both proponents and opponents alike).
Sorry, it won't work. I've known too many engineers.
Myth: Small diameter wheels have difficulty on rough surfaces and bumps.
Fact: While this may be true if tire width is not increased to compensate, since the tires used by smaller wheels require less material to go around the circumference of the wheel, the weight penalty for increasing tire width is much much lower. One could argue that larger diameter wheels actually have more difficulty on rough surfaces and bumps because they can't accommodate wide tires without a significant weight penalty.
One could argue whatever one likes, but if one were to ride one's small- and large-wheel bikes on the same cobblestone street in lower Manhattan, as this one has, one would be likely to expand one's argument as one's rattling fillings provided new data.
Myth: Small wheels are dangerous because they are more likely to fall into potholes and stop short, sending the rider flying.
Fact: No. Wheels do not fall into potholes at speed, they mostly sail over them (falling mere centimeters for every meter traveled forward at even moderate cycling speeds). Moreover, naturally occurring potholes do not have tall steep edges like curbs, so there is no reason to expect a wheel that has fallen in to stop as opposed to roll out as if going over a miniature ramp. The actual danger of a pothole is that the impact may cause one to lose control of the bike as the sideways forces on the wheel surprise or overpower the rider who may then be unable to correct the steering before crashing. If this were not the case it would be near impossible for a pothole to cause a crash with a 26" wheel (or even a 20" wheel) and, yet, we know that hitting a pothole is not an uncommon crash cause. So small wheels are actually safer because they give the rider more leverage to hold the handlebars steady and allow the rider to correct the steering more quickly. Wheel trail can not help in these situations because the self correcting property of trail depends on the interaction between the rolling wheel and an even road, which is literally undermined in the case of a pothole.
There's nothing even vaguely "scientific" (your word) in this. Wheels do fall into potholes. Smaller ones fall in more. "At speed" means nothing. "Naturally occurring" is not a useful distinction when discussing potholes. The leverage you're saying gives the rider an advantage also means the weight of your hands can make the bike fall over faster.
I've also noticed that my folder is much more prone to pitching up its back wheel in a panic stop than my road bike. There are reasons besides wheel size for this, but if you're on a small-wheeled bike, chances are good you're on a folder; and things like trail, wheelbase, and position of center of gravity relative to front axle are a little dicier than on your 700cm non-folder.
So maybe I can't blame the wheel size, but I can blame the nature of a small-wheeled bike.
You know the joke about the engineer and the guillotine, right?